King crabs invading Norwegian waters from neighbouring Russia have been found further north than ever before.

This is the introduction of an alien species... we should do what we can to get rid of them

Jan Sundet

A Norwegian scientist, Jan Sundet, said this week they had been caught as far as 215 kilometres (115 miles) from the mainland.

The crabs - which can weigh up to eight kilogrammes and measure more than a metre across - first entered Norwegian waters 30 years ago, eating everything in their path and killing the native crab population.

"This is the introduction of an alien species, which is always negative," said Mr Sundet, of the Norwegian Institute of Fisheries and Aquaculture Research.

"We should do what we can to get rid of them."

Cod replacement

The King crabs have no natural foe in the area, and have left parts of the sea floor devoid of life.

For fishermen, however, the invasion is not entirely bad news.

They represent an alternative catch to cod, and sell for about five times as much per kilo.

Norway first allowed them to be caught commercially in 2001, and has doubled the annual quota to 200,000 crabs for 2003.

Mr Sundet said no-one has accurately counted the number of King crabs in Norwegian waters, but media reports suggest there could be one million of them.

The big crabs originally came from the Kamchatka peninsula in the Russian Far East.

They began their march into Norway from Russia's Kola peninsula, in search of new breeding grounds.